The present invention relates in general to apparatus for transporting paper signatures or the like into a processing device. More particularly, the invention pertains to forming a uniform running shingle of signatures traveling at high speed from signatures which have been preformed or which are somewhat randomly received from another machine or a storage area.
Newspaper and booklet presses conventionally include transport devices which bring out multiple sheet, folded assemblies in an overlapped running shingle. The assemblies are called "signatures" and their folded edges are called "spines". The signatures in a running shingle move with the spines as leading edges, and with each signature set back slightly (here called the shingle set back SSB) from the one that precedes it so that the shingle is constituted by overlapped signatures. If the set back from one leading edge (spine) to the next is one third of the length of a signature, for example, the shingle in total thickness is equal to three times the thickness of a single signature. In such a shingle moving on an underlying conveyor belt, the leading two-thirds of each signature rests on preceding signatures and only the trailing one-third is in contact with the belt.
Running shingles have been formed as a convenient way of transporting signatures from one location to another and into further processing devices such as quarter-folders (to make a double-folded signature), to labeling machines, to stackers, etc. As they come from a printing press, for example, the signatures are already in a shingle running at high speed and they may conveniently be fed into various processing devices.
For various reasons, however, the output of a printing press is often stored for subsequent processing. A primary reason is that the processing device simply runs more slowly than the press and cannot keep up; another reason is simply because production schedules may call for storing press output and mailing (or otherwise processing) at a later date. Some machines, including some printing presses, may produce signatures somewhat randomly rather than in a nicely formed running shingle. In any of these cases, the output of a signature-forming machine is converted into stacks for storage--and the stacks are later fed into a processing device of one kind or another.
Most processing devices (e.g., rotary trimmers or quarter-folders) accept as their input a running shingle of signatures. Thus, there is a need to convert preformed and stack-stored signatures (or randomly received signatures or a rough shingle) into a running shingle for in-feed into a processing device.
The present invention performs that function and, in one preferred embodiment to be described, handles multi-page, single-fold signatures of flexible newsprint paper. As will be apparent, however, the uses and advantages of the invention are not limited to paper nor even to folded signatures. On the contrary, essentially any item--which is reasonably flexible, which has a reasonably rigid leading edge (whether or not folded to constitute a "spine"), and which can be conveyed in overlapped relation as a shingle--may be accommodated by the present invention. Thus, for example, plastic sheets of reasonable thickness, cardboard sheets, or flat bags may be handled in the fashion to be described. As a generic name for all such kinds of items, the term "document" will be here employed; it is to be understood that this is to be taken without regard to whether there is any printed matter on the item, whether the item is indeed folded so as to have a spine, or the particular material of which the item is constituted. The folded signatures treated in the following detailed description are simply an example of what is generically defined here as "documents".
There has been an historical problem of how to manipulate pre-stored or randomly received documents into a high-speed, uniform running shingle. The need for high running velocity is critical because some processing devices are capable of running at high speed --and if the shingle incoming to them is slow--their production capabilities are wasted. A uniform shingle is demanded for reliability of operation and avoidance of jams in a processing device.